I've been using Harbor Freight's cheap-o Drillmaster impact driver for awhile now, it's wonderful for working on the road... nobody tries to steal it, if they did it'd be cheap to replace.
The driver itself works fine, but the batteries are really slow to charge. They don't sell a fast charger for it, only a tiny 4 hour charger. They do have a fast charger that fits their higher quality drills... which are also 18v NiCAD batteries, but they aren't interchangeable. So I hacked it to fit.
I wouldn't normally video stuff like this, but I couldn't find it online anywhere else. Maybe this will help someone.